This invention relates to a presser foot for a sewing machine.
The mass-production garment industry is now heavily mechanised, and one technique that is commonly used for assembling together two or more garment parts is to use a stitching jig. Such jigs comprise a lower plate and an upper plate between which the garment parts may be held, and fulling means may also be present between the upper and lower plates in order that "fullness" may be introduced into required areas of the fabric. The lower plate of the jig has a guide track which, in use, is engaged with a guide member on the base plate of a sewing machine, with the fabric parts to be stitched together overlying the guide track. The guide member has an opening for the needle of a sewing machine and an elongated opening adjacent to the needle opening through which a trimming knife may be reciprocated. In use, the loaded jig is driven so that it moves beneath the needle and the trimming knife, with the guide track following the guide member. A line of stitching between the garment parts is effected along the line defined by the guide track, and unwanted material lying outside the stitch line is cut away by the trimming knife. The resulting composite garment part can then be removed from the jig for further processing.
It will be appreciated that the trimming knife cuts simultaneously through all the fabric layers, and thus that the distance from the stitch line to the free edge of each layer will be substantially identical.
In the manufacture of some high quality garments, a so-called "feathered edge" (or step-back edge) is required, and in order to form such an edge it is a requirement that the trimmed edges of the respective layers of fabric should not be equidistant from the stitch line, but that a further layer of fabric should extend beyond a second layer by a predetermined distance along the whole of the trimmed edge. Thus, the edge of the second layer is substantially uniformly stepped back from the edge of the first layer. The resultant single layer strip of first fabric is necessary in forming the feathered edge. This type of edge can be hand made, but has proved difficult to automate.
Our prior patent GB-B-2201694 relates to a presser foot for a sewing machine which is capable of automatically effecting a stepped back edge as fabric is fed through the machine. Although successful on some fabrics, the presser foot disclosed therein did not always give good results with all fabrics, and it was also necessary to trim more fabric than had previously been conventional, thereby leading to more waste. The present invention provides a presser foot which seeks to avoid these disadvantages.